This invention relates to the attachment of scaffolding platforms, workmen's platforms or cradles to flanged girders of steel or like material and is particularly concerned with a roller fitting adapted to be secured to a length of scaffolding and to suspend said scaffolding from such girders.
One known arrangement for suspending a workmen's cradle is disclosed in British Pat. No. 1,045,146 in which the cradle is suspended from a tubular rail 28 by means of a strap 32 which is hooked around a rod 29 which in turn carries stub shafts 31 on which are rotatably mounted rollers 30 which engage the rail 28. With this arrangement, the rod 29 and rollers 30 must be located above the rail 28 and this arrangement cannot be used for suspending a platform from a girder having horizontally extending flanges because the strap would foul the outside edge of one of the flanges. Moreover, the rod 29 would have to be located above the girder and access to the top of a girder is usually not possible in practice.
Another arrangement for suspending a platform from a flanged girder is disclosed in British Pat. No. 776,642 in which rollers 24 are arranged to run along horizontal flanges extending from both sides of a girder or track 22. The two rollers 24 are mounted on a so-called traveller 21 which carries a pulley block 20 and the platform is suspended by a cable 19 from the pulley block. It is clear from this arrangement that both flanges of the girder must be engaged by rollers and that if one of the rollers were to be omitted the platform could not be reliably suspended from the girder and the traveller 21 could fall off the girder with possible fatal results for anyone standing on the platform at the time.
Moreover, in both of the above-described arrangements, the platform or cradle is suspended by ropes or cables which are prone to breakage and cannot therefore be regarded as being absolutely safe.